RF power transistor

Abstract

A method for manufacturing a silicon bipolar power high frequency transistor device is disclosed. A transistor device according to the present method is also disclosed. The transistor device assures conditions for maintaining a proper BVCER to avoid collector emitter breakdown during operation. According to the method an integrated resistor is arranged along at least one side of a silicon bipolar transistor on a semiconductor die which constitutes a substrate for the silicon bipolar transistor. The integrated resistor is connected between the base and emitter terminals of the silicon bipolar transistor. The added integrated resistor is a diffused p+ resistor on said semiconductor die or a polysilicon or NiCr resistor placed on top of the isolation layers. In an interdigitated transistor structure provided with integrated emitter ballast resistors the added- resistor or resistors (20) will be manufactured in a step simultaneously as producing the ballast resistors.

What is claimed is:  
     
       1. A power transistor device comprising: 
       an integrated resistor along at least one side of a silicon bipolar transistor in a semiconductor die comprising a substrate for said silicon bipolar transistor; and  
       wherein said integrated resistor is connected between base and emitter terminals of said silicon bipolar transistor, the integrated resistor being adapted to maintain a proper BV CER  to avoid collector emitter breakdown.  
     
     
       2. The power transistor device of  claim 1 , wherein said integrated resistor comprises: 
       a diffused p +  resistor on said semiconductor die; and  
       wherein a base/emitter voltage is always lower than a collector voltage.  
     
     
       3. The power transistor device of  claim 1 , wherein said integrated resistor comprises a resistor selected from the group consisting of polysilicon and NiCr resistors, the resistor being positioned on top of isolation layers. 
     
     
       4. The power transistor device of  claim 1 , wherein the silicon bipolar transistor comprises an RF power transistor, the RF power transistor comprising an interdigitated structure provided with a plurality of integrated emitter ballast resistors adapted to prevent thermal run away. 
     
     
       5. The power transistor device of  claim 4 , wherein said RF power transistor is provided with an integrated bypass capacitor for each integrated emitter ballast resistor, said integrated bypass capacitor being adapted to increase the gain of said RF power transistor.